From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DB153C43381 for ; Thu, 21 Feb 2019 16:07:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B3F412083E for ; Thu, 21 Feb 2019 16:07:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728342AbfBUQHK (ORCPT ); Thu, 21 Feb 2019 11:07:10 -0500 Received: from mx1.redhat.com ([209.132.183.28]:40012 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728235AbfBUQHJ (ORCPT ); Thu, 21 Feb 2019 11:07:09 -0500 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 5B3D537F46; Thu, 21 Feb 2019 16:07:09 +0000 (UTC) Received: from redhat.com (unknown [10.20.6.236]) by smtp.corp.redhat.com (Postfix) with ESMTPS id DBE9A1001DD8; Thu, 21 Feb 2019 16:06:57 +0000 (UTC) Date: Thu, 21 Feb 2019 11:06:55 -0500 From: Jerome Glisse To: Peter Xu Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, David Hildenbrand , Hugh Dickins , Maya Gokhale , Pavel Emelyanov , Johannes Weiner , Martin Cracauer , Shaohua Li , Marty McFadden , Andrea Arcangeli , Mike Kravetz , Denis Plotnikov , Mike Rapoport , Mel Gorman , "Kirill A . Shutemov" , "Dr . David Alan Gilbert" Subject: Re: [PATCH v2 05/26] mm: gup: allow VM_FAULT_RETRY for multiple times Message-ID: <20190221160612.GE2813@redhat.com> References: <20190212025632.28946-1-peterx@redhat.com> <20190212025632.28946-6-peterx@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20190212025632.28946-6-peterx@redhat.com> User-Agent: Mutt/1.10.0 (2018-05-17) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Thu, 21 Feb 2019 16:07:09 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Feb 12, 2019 at 10:56:11AM +0800, Peter Xu wrote: > This is the gup counterpart of the change that allows the VM_FAULT_RETRY > to happen for more than once. > > Signed-off-by: Peter Xu Reviewed-by: Jérôme Glisse > --- > mm/gup.c | 17 +++++++++++++---- > 1 file changed, 13 insertions(+), 4 deletions(-) > > diff --git a/mm/gup.c b/mm/gup.c > index fa75a03204c1..ba387aec0d80 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -528,7 +528,10 @@ static int faultin_page(struct task_struct *tsk, struct vm_area_struct *vma, > if (*flags & FOLL_NOWAIT) > fault_flags |= FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_RETRY_NOWAIT; > if (*flags & FOLL_TRIED) { > - VM_WARN_ON_ONCE(fault_flags & FAULT_FLAG_ALLOW_RETRY); > + /* > + * Note: FAULT_FLAG_ALLOW_RETRY and FAULT_FLAG_TRIED > + * can co-exist > + */ > fault_flags |= FAULT_FLAG_TRIED; > } > > @@ -943,17 +946,23 @@ static __always_inline long __get_user_pages_locked(struct task_struct *tsk, > /* VM_FAULT_RETRY triggered, so seek to the faulting offset */ > pages += ret; > start += ret << PAGE_SHIFT; > + lock_dropped = true; > > +retry: > /* > * Repeat on the address that fired VM_FAULT_RETRY > - * without FAULT_FLAG_ALLOW_RETRY but with > + * with both FAULT_FLAG_ALLOW_RETRY and > * FAULT_FLAG_TRIED. > */ > *locked = 1; > - lock_dropped = true; > down_read(&mm->mmap_sem); > ret = __get_user_pages(tsk, mm, start, 1, flags | FOLL_TRIED, > - pages, NULL, NULL); > + pages, NULL, locked); > + if (!*locked) { > + /* Continue to retry until we succeeded */ > + BUG_ON(ret != 0); > + goto retry; > + } > if (ret != 1) { > BUG_ON(ret > 1); > if (!pages_done) > -- > 2.17.1 >